Effect on pulmonary functions of dust exposed rice mill workers in comparison to an unexposed population

Abstract

BACKGROUND: Paddy milling is the oldest and largest agro-processing industry in India. A large number of workers are employed in the rice mills where they are potentially exposed to dust. It has been shown that exposure to dust results in a high prevalence of respiratory diseases, such as asthma, chronic bronchitis, extrinsic allergic alveoli ties, toxic syndrome, and interstitial lung disease. OBJECTIVE: The aim of this study was to investigate the effect of dust on rice mill workers’ health using lung function tests with comparison to an unexposed population. PARTICIPANTS: Two hundred eighteen rice mill workers (exposed volunteers) were randomly selected from 25 rice mills in Assam, India. Participants were 18-60 years with at least one year of work experience. Further, 377 volunteers who were not exposed to dust and having similar demographic characteristics also participated as a control group. METHOD: Pulmonary function tests were conducted for all participants by spirometry. The tests included forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC (%), peak expiratory flow (PEF) and forced expiratory flow during the middle half of a forced vital capacity (FEF25-75%). Values from exposed workers were compared with the unexposed volunteers. RESULTS: It was observed that the lung function parameters FVC, FEV1, PEF and FEF25-75% in exposed workers were significantly decreased compared with unexposed volunteers. There were also significantly decreased FVC, FEV1, FEV1/FVC%, PEF and FEF25-75% with increase in age and duration of dust exposure. It was further observed that 48% and 32% of the total male and female volunteers, respectively, had evidence of lung disease. Irrespective of gender, approximately 45% of mill workers had evidence of lung disease, of which 21% was restrictive and 24% was obstructive. CONCLUSION: Compared with unexposed controls, rice mill workers have a greater prevalence of respiratory disease based on pulmonary function tests.